%difference of Total Host Writes and Total NAND Writes are too huge

[junzhi2002]

I just read up some articles about this topic as my SSD dropped from ~75% health to 63% health in just 2 months (not like mine is any good), is there any explanation to the huge difference between Total Host Writes and Total NAND Writes?
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[Eigenvektor]

6 minutes ago, junzhi2002 said:

is there any explanation to the huge difference between Total Host Writes and Total NAND Writes?

I've found an answer on https://superuser.com/a/1399085, that indicates that this can be an issue with some SSDs in combination with e.g. disk encryption or simply be the result of a bug in the disk's controller.

 

Wikipedia has a more technical explanation why the NAND Writes value is larger than the Host Writes value: https://en.wikipedia.org/wiki/Write_amplification

[NewMaxx]

Well the SMART data says 19.67TB written for host (614599x32) vs. 20.06TB written on NAND (626993x32). HWiNFO might be reading it wrong, you can also try CrystalDiskInfo and/or Hard Disk Sentinel.

 

That being said, your average erase count of 561 indicates around that many program/erase cycles. Given the health %, this indicates a maximum of around 1500 PEC, which in fact is what SMART indicates.

 

Something is definitely off here, particularly your minimum versus maximum erase counts are way too far apart.

[junzhi2002]

7 hours ago, NewMaxx said:

Well the SMART data says 19.67TB written for host (614599x32) vs. 20.06TB written on NAND (626993x32). HWiNFO might be reading it wrong, you can also try CrystalDiskInfo and/or Hard Disk Sentinel.

 

That being said, your average erase count of 561 indicates around that many program/erase cycles. Given the health %, this indicates a maximum of around 1500 PEC, which in fact is what SMART indicates.

 

Something is definitely off here, particularly your minimum versus maximum erase counts are way too far apart.

If you dont mind, can you explain why the min/max erase counts should not be too far apart and 

 

7 hours ago, NewMaxx said:

That being said, your average erase count of 561 indicates around that many program/erase cycles.

does this part means that my ssd got written way too much? Not sure what is going on but the past few months i have been filling this ssd to ~80% its capacity and its constantly doing garbage collection 

 

8 hours ago, Eigenvektor said:

I've found an answer on https://superuser.com/a/1399085, that indicates that this can be an issue with some SSDs in combination with e.g. disk encryption or simply be the result of a bug in the disk's controller.

 

Wikipedia has a more technical explanation why the NAND Writes value is larger than the Host Writes value: https://en.wikipedia.org/wiki/Write_amplification

[NewMaxx]

15 hours ago, junzhi2002 said:

If you dont mind, can you explain why the min/max erase counts should not be too far apart and 

 

does this part means that my ssd got written way too much?

If a drive is doing wear-leveling the erase counts of the blocks should be pretty close together. You have some blocks that have been erased more than ten times more than others. To be fair, not all blocks are created equal, for a variety of reasons; for example, blocks on upper layers have better retention properties. Nevertheless, the disparity in min/max should be relatively small. There's two primary kinds of wear-leveling but in this case blocks with stale data are supposed to be refreshed once other blocks have high erase counts, for example. This keeps the counts closer together.

 

561 PEC is relatively high for a consumer drive but not alarmingly so, depending on the age of the device. It does indicate a lot of writes.